This invention relates generally to antennas, and more particularly to a mechanism for dynamically varying the beamwidth and azimuth scan angle of such antennas.
Antenna construction generally includes a plurality of antenna columns defining a signal beamwidth and azimuth scan angle. The beamwidth of an antenna may be modified by varying the phase of an electrical signal applied to the columns. Advancements in antenna technologies include providing each antenna column with an individually-coupled, mechanical phase shifter. Systems having a phase shifter dedicated to each column of an antenna allow improved beamwidth and azimuth scan angle control.
While antenna configurations having individually-coupled phase shifters provide increased wave propagation control, still greater beamwidth and azimuth scan angle variability is desired. Additionally, an individually-coupled phase shifter configuration may fail to provide sufficient control for certain signal diversity applications, such as where dual dipole elements are desired. Signal diversity generally involves separating signals for subsequent processing. For instance, two signals having different polarizations may be combined upon transmittal so that their aggregate signal strength is sufficient to allow the composite signal to reach respectively polarized antenna columns.
Antennas having dual dipole elements allow a single column to receive/transmit both polarizations, avoiding maintenance, space and aesthetic drawbacks associated with greater numbers of single pole antennas. However, diversity benefits associated with dual dipole elements may remain unrealized in conjunction with the individually-coupled phase shifter configuration incorporated herein, which would facilitate improved propagation control in only one of the two polarizations.
Consequently, there is a need to provide wider dynamic wave propagation control. Further improvements are also possible where each column of an antenna includes multiple poles.